Golf balls can generally be divided into two classes: solid and wound. Solid golf balls include one-piece, two-piece (i.e., solid core and a cover), and multi-layer (i.e., solid core of one or more layers and/or a cover of one or more layers) golf balls. Wound golf balls typically include a solid, hollow, or fluid-filled center, encased in a layer of tensioned elastomeric material and a cover layer. Solid balls have traditionally been considered longer and more durable than wound balls, and, until recently, were considered to lack the particular “feel” that was provided by the wound construction and typically preferred by accomplished golfers.
By altering solid golf ball construction and the composition of the individual layers, however, manufacturers can vary a wide range of playing characteristics, such as resilience, durability, spin, and “feel,” each of which can be optimized for various playing abilities, allowing solid golf balls to provide feel characteristics more like their wound predecessors.
The core is considered the ‘engine’ of the golf ball. Generally, golf ball cores constructed with a polybutadiene-based polymer composition. Compositions of this nature are constantly being tweaked in an effort to provide a targeted or desired coefficient of restitution, compression, spin rate, and/or “feel.” This is a difficult task, however, given the physical limitations of currently-available polymers.
As such, there remains a need for improved golf ball core (and core layer) materials and/or blends. While metallic fatty acid salts, such as zinc stearate, have been used in golf ball formulations for many years, cis-to-trans conversion is relatively new. Higher levels of metallic fatty acid salts are generally considered to be detrimental (i.e., lower COR and compression). It has been determined, however, that golf ball core formulations comprising elevated levels of a metallic fatty acid salt, preferably zinc stearate, in combination with a cis-to-trans catalyst and low levels of peroxide, result in unexpected improvement in COR and compression, without the loss of both typically associated with the addition of high levels of metallic fatty acid salts.